1. Field
Example embodiments relate to an optical film having a graded refractive index and a method of manufacturing the same, and more particularly, to an optical film having a graded refractive index, including one or more antireflection films composed of a mesoporous material having a plurality of pores of a uniform size, in which the pores of the mesoporous material are filled with air or a filler having a refractive index different from that of the mesoporous material, and thus the volume ratio of mesoporous material to filler in the pores thereof is controlled, thereby obtaining a desired magnitude of effective refractive index and ensuring a refractive index distribution in which the refractive indexes sequentially change, resulting in high antireflection performance, and to a method of manufacturing the same.
2. Description of the Related Art
An antireflection film means a film for preventing the reflection of light. For example, an antireflection film useful in the visible light range may be applied to various display devices including plasma display panels (PDPs) in a manner such that it is spaced by a predetermined interval apart from the surface of the display device to improve contrast and image quality, and may constitute an optical filter along with a selective light absorbing layer for improving a color tone and an electromagnetic wave blocking layer for blocking electromagnetic waves. In addition, an antireflection film that is useful in the near infrared light range may be widely applied to various fields including optical communication and optoelectronic devices.
However, conventional antireflection film coating techniques are problematic in that the refractive index is drastically changed at the interface of an optical device, undesirably increasing reflected light. Thus, as attempts to solve the problem in which the efficiency of the optical device is drastically decreased, there has been proposed the formation of a monolayer film which satisfies the relation of sqrt (n1*n2) (n1: refractive index of material, n2: refractive index of air) as thick as ¼ of the incident wavelength in the case where light is incident perpendicular to the interface of the optical device. However, in the case where light is incident on the optical device under conditions in which the incident wavelength is not a short wavelength but is a long wavelength or the incident angle is not a right angle but is an obtuse angle, antireflection performance is remarkably decreased.
Moreover, the efficiency of the device is intended to be improved by providing the antireflection film in the form of a multilayer of three layers or more, instead of a monolayer form. In this case, however, expensive equipment for precisely controlling the thickness of each layer and vacuum equipment are required, making it difficult to realize mass production.